Method for catalytic conversion of hydrocarbons



June 27, 1967 J. P. SHAMBAUGH 3,328,292

METHOD FOR CATALYTIC CONVERSION OF HYDROCARBONS Filed May 11, 1964CHARGE 15 STOCK FILTER FRESH CATALYST Fl/EL A6 REQll/RED 56 l I l I I I1 I I 1 ALTERNATE a 2 46 OES/REO 7'0 STORAGE United States Patent3,328,292 METHOD FOR CATALYTIC CONVERSION (1F HYDROCARBONS James P.Shambaugh, Huntington, N.Y., assignor to Mobil 0i] Corporation, acorporation of New York Filed May 11, 1964, Ser. No. 366,477 9 Claims.(Cl. 208-120) This invention relates to improvements in the catalytictreatment of hydrocarbons and more particularly to a catalytic processand equipment for treatment of hydrocarbons in the presence ofsuperactive catalysts.

Since the commercial development of catalytic cracking over 25 yearsago, substantially all cracking operations in the industry have been ofthe type wherein petroleum oils boiling in the range above 400 F. havebeen fed in liquid form or in vapor form or mixed liquid-vapor form intocatalyst-containing reactors at conditions to achieve rather hightemperatures, generally in excess of 800 F. in order to crack the oilsand secure petroleum oil fractions boiling in the motor fuel oil range.In those cases wherein liquid or mixed liquid-vapor feed is fed to thereactor, there appears to occur rapid vaporization of the liquid portionof the feed at the catalyst surface or before reaching the same so thatin effect the feed at the moment of cracking is substantially all invapor form. Though the development of catalytic cracking of the naturejust described has been so successful as to warrant the building ofgigantic installations during the past 25 years at a cost running intohundreds of millions of dollars, there yet exist a number of problemsand disadvantages associated with the process even today which are stillto be overcome. Thus, though the conversions obtained under the rathersevere cracking conditions employed today are considered fairlysatisfactory, the product selectivity and product distribution obtainedat such conversions still leaves room for improvement. Conversion may beexpressed as the quantity of charge to the catalytic cracking processminus the amount of recycle divided by the amount of charge. The recycleis defined as everything in the effluent boiling above gasoline. Inpointing out that conversion is considered fairly satisfactory in theprocesses used today at conventional cracking conditions while productselectivity and product distribution are also fairly satisfactory, itwould be desirable to decrease the relative quantity of coke producedduring cracking and also to decrease the amount of dry gas made.

Though the above facts have suggested the desirability of conductingcatalytic cracking under less severe cracking conditions, i.e., underconditions of pressure and temperature such that cracking is affected atlower temperatures, either entirely or predominantly in the liquidphase, efforts along these lines have not been satisfactory for a numberof reasons. Liquid phase cracking at lower temperatures has resulted inuneconomically low reaction rates and conversions. Moreover, though theformation of gas during cracking has been reduced, there has not been acorresponding reduction in coke make. In fact, the necessity forprolongation of the period of catalyst contact, because of lowerreaction rates, has sometimes resulted in even higher coke make thanoccurs by cracking of vapor or mixed liquid-vapor under more severeconditions.

The present invention relates to a process and apparatus which overcomesthe disadvantages of the prior art in conducting catalytic cracking atlower temperatures than conventional, in a predominantly liquid phase,with a suitable catalyst. According to the present invention catalyticcracking occurs in contact with a superactive catalyst in the bottomsection of a fractionating column under liquid phase crackingconditions. The catalyst ice may be continuously drawn off, regeneratedand returned to the column, and the products formed in the reaction passupwardly into the top section of the fractionator for fractionating intothe desired number of product fractions, thus eliminating need forseparate fractionation and in detail hereafter, is charged into thebottom section 12 of the fractionator. An inlet conduit 18 conducts thecharge stock into the bottom section 12. As necessary to supply heat tothe reaction catalyst slurry may be withdrawn from the bottom section 12through outlet line 20, by a slurry pump 22, to a heater 24 and thenceis returned to the bottom section 12 through line 26.

Another stream of catalyst slurry is drawn off through line 28 and isfed to a continuous filter 30 or other means of liquid-solid separation.The liquid product is removed from the separator through line 32 and maybe removed to storage through line 34 or when desired to minimize thequantity of bottoms product, repumped into the bottom section 12 by pump36 and line 26. The catalyst fromthe separator 30 in the form of filtercake, for example, may then be regenerated as for example in the heater24; or in any other convenient form of regenerator, supplying all or aportion of the heat necessary for reaction, with supplemental fuel 35fired into the heater 24 or the regenerator as necessary.

The catalyst may be discarded, or, after regeneration, the catalyst isreslurried at by the clarified oil from pump 36 or by fresh charge stockfrom line 42. The -re' slurried catalyst is returned to the bottomsection 12 through line 26 after merging with the recirculated catalystslurry from the heater 24.

The regenerated catalyst passing from the filter 30 through the heater24 may be conveyed by a traveling grate shown schematically at 44.

The charge stock may be any hydrocarbon stream which is to be convertedto a more valuable (usually lighter) product. It is contacted with thesuperactive catalyst 16 in the reaction zone in a predominantly liquidstate. This is accomplished by operating under conditions that maintainthe uncracked charge material in a liquid phase. Such conditions includetemperatures in the range of 500-900 F., pressure in the range of 10 to1000 p.s.i.a, space velocities in the range of 10-1000 equivalentweights of oil per weight of catalyst per hour (w./hr./w.), and 0.01 to10 equivalent weights of catalyst per weight of oil (C/O).

The pressure in the reaction section of the fractionator will becontrolled by conventional overhead pressure con-- trols, whereas thespace velocity (w./hr./w.), catalyst to oil ratio (C/O), and recycleratio will be controlled by the rate at which the catalyst-oil slurry iswithdrawn from the tower bottom through line 20.

' When only low conversion is desired, the clarified oil from the filter30 may be rejected as a bottom product through line 34.

Other means of regeneration other than combustion such as in the heater24 may be utilized, such as removal of the heavy hydrocarbons by asolvent or other methods.

The top section 14 of the tower is provided with con-- ventionalfractionating plates with a plurality of side streams drawn otf at 52,54 and 56. The side stream 52 and 54 are conducted to normal stripping,cooling and product blending or further processing. The stream 56containing gas and gasoline is subjected to the normal recovery andseparation steps with the refiux being returned via line 58.

The catalysts useful in the present invention are as indicated inco-pending patent application Ser. No. 208,512 filed July 9, 1962, newsuperactive catalysts which have a relative activity of as high as10,000 times that of presently used catalysts in the cracking ofhydrocarbons. Although technology is not now available for achievingfull use of these catalysts, it has been found that these materialsexhibit product selectivity which is extremely attractice, since theratio of gasoline yield to coke make in gas oil cracking has been foundto be markedly greater than that of conventional catalysts.

Crystalline aluminosilicates are materials of ordered internal structurein which atoms of alkali metal, alkaline earth metal or metals inreplacement thereof, silicon, aluminum and oxygen are arranged in adefinite and consistent crystalline or ordered pattern. Such structurecontains a large number of small cavities, interconnected by a number ofstill smaller channels. These cavities and channels are preciselyuniform in size. The interstitial dimensions of openings in the crystallattice limit the size and shape of the molecules that can enter theinterior of the aluminosiilcate and it is such characteristic of manycrystalline zeolites that has led to their designation as molecularsieves.

Zeolites having the above characteristics include both natural andsynthetic materials, for example, chabazite, gmelinite, mesolite,ptiliolite, mordenite, natrolite, nepheline, sodalite, scapolite,lazurite, leucrite, and cancrinite. Synthetic zeolites may be of the Atype, X faujasite type, Y faupasite type, T type or other well knownform of molecular sieve, including ZK zeolites such as those describedin copending application Ser. No. 134,841 filed Aug. 30, 1961.Preparation of various examples of such zeolites is known, having beendescribed in the literature, for example .A type zeolite in U.S.2,882,243 X faujasite type zeolite in U.S. 2,882,244; other types ofmaterials in Belgium Patent No. 577,642 and in U.S. 2,950,952. Asinitially prepared, the metal of the aluminosilicate is an alkali metaland usually sodium. Such alkali metal is subject to base-exchange with awide variety of other metal ions. The molecular sieve materials soobtained are unusually porous, the pores having highly uniform moleculardimensions, generally between about 3 and possibly about 15 Angstromunits in diameter. Each crystal of molecular sieve material containsliterally billions of tiny cavities or cages interconnected by channelsof unvarying diameter. The size, valence and amount of the metal ions inthe crystal can control the effective diameter of the interconnectingchannels.

At the present time, there are commercially available materials of the Aseries and of the X faujasite series. A synthetic zeolite known asMolecular Sieve 4A is a crystalline sodium aluminosilicate havingchannels of about 4 Angstroms in diameter. In the hydrated form, thismaterial is chemically characterized by the formula:

The synthetic zeolite known as Molecular Sieve 5A is a crystallinealuminosilicate salt having channels about 5 Angstroms in diameter andin which substantially all of the 12 ions of sodium in the immediatelyabove formula are replaced by calcium, it being understood that calciumreplaces sodium in the ratio of one calcium for two sodium ions. Acrystalline sodium aluminosilicate having pores approximately Angstromsin diameter is also available commercially under the name of MolecularSieve 13X. The letter X is used to distinguish the interatomic structureof this zeolite from that of the A crystals mentioned above. Asprepared, the 13X material contains water and has the unit cell formula:

sal 2)ss( 2)1os]- 2 The 13X crystal is structurally identical withfaujasite,

a naturally occurring zeolite. The synthetic zeolite known as MolecularSieve 10X is a crystalline aluminosilicate salt having channels about 10Angstroms in diameter and in which a substantial proportion of thesodium ions of the 13X material have been replaced by calcium.

Molecular sieves of the X faujasite series are characterized by theformula:

where M is Na+, Ca++ or other metal ion-s introduced by The structureconsists of a complex assembly of 192 tetrahedra in a large cubic unitcell 24.95 A. on an edge. Both the so-called X and the so-called Y typecrystalline aluminosilicates are faujasites and have essentiallyidentical crystal structures. They differ from each other only in thattype Y aluminosilicate has a higher SiO A1 0 ratio than the X typealuminosilicate.

The alkali metal generally contained in the naturally occurring orsynthetically prepared zeolites prescribed above may be replaced byother metal ions. Replacement is suitably accomplished by contacting theinitially formed crystalline aluminosilicate with a solution of anionizable compound of the metal ion which is to be zeoliticallyintroduced into the molecular sieve structure for a sufficient time tobring about the extent of desired introduction of such ion. After suchtreatment, the ion exchanged product is water washed, dried andcalcined. The extent to which exchange takes place can be controlled.

Naturally occurring or synthetic crystalline aluminosilicates may betreated to provide the superactive alumino-silicates employed in thisinvention by several means, such as base exchange to replace the sodiumwith rare earth metal compounds, by base exchange with ammoniumcompounds followed by heating to drive off NH ions, having an H or acidform of aluminosilicates.

by treatment with mineral acid solutions to arrive at a hydrogen or acidform, and by other means. These treatments may be followed by activityadjusting treatments, such as steaming, calcining, dilution in a matrixand other means. Explanation of the methods of preparing such catalystsis made in co-pending application Ser. No. 208,- 512 filed July 9, 1962,now abandoned.

It should be noted that the catalysts used in this invention may be acomposite of the superactive aluminosilicate and a relatively inertmatrix material, or it may consist only of the superactive catalyst. Ifthe catalyst consists of a composite, it may be produced in the form ofpellets, beads, or particles such as may be produced by spray drying.The matrix material may be any hydrous oxide gel, clay or the like. Thematrix material used should have a high porosity in order that thereactants may obtain access to the active component in the catalystcomposite. A high porosity matrix of the hydrous oxide type may be usedin these composite catalysts, such as silica-alumina complexes,silica-magnesia, silica gel, high porosity clay, alumina, and the like.

The pellets or beads of the composite catalysts may be prepared bydispersing the aluminosilicate in an inorganic oxide sol according tothe method described in U.S. Patent No. 2,900,399 and converted to agelled bead according to the method described in U.S. Patent No.2,384,946.

The crystalline aluminosilicate material must have a pore size orintracrystalline aperture or channel size sufficiently great to admitdesired reactants. 5 A. is approximately the minimum pore size soacceptable.

The composite may contain from 5-95 percent of the matrix material.

Utilizing the conditions in the reaction of:

Pressure p.s.i.a 10-1000 Temperature F 500-900 Space velocity (w./h./W.)10-1000 C/O 0.01-10 Recycle ratio 0-10 a product distribution can beobtained as follows, expressed in percent weight of charge stock:

Gas 1-15 C 3-25 Gasoline 2075 Side streams -40 Bottoms 035 Coke %5Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modification andvariations may be resorted to, without departing from the spirit andscope thereof, as those skilled in the art will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

What is claimed is:

1. A method for efiecting liquid phase conversion of hydrocarbons whichcomprises forming a liquid phase slurry of fresh hydrocarbon feed andfinely divided high activity catalyst particles, introducing said slurryto a hydrocarbon conversion zone maintained under temperature andpressure conditions sufficient to convert a portion of said hydrocarbonsto vaporous conversion products, passing vaporous hydrocarbon conversionproducts overhead to a fractionation zone, removing a first portion ofslurry from the conversion zone, separating said first portion into aliquid hydrocarbon phase and a catalyst particle phase, regenerating bycombustion said catalyst particles phase, reslurrying regeneratedcatalyst particles with at least said liquid hydrocarbon phase andrecycling reslurried material to said conversion zone.

2. The method of claim 1 wherein the amount of hydrocarbon-catalystslurry Withdrawn from the reaction zone is controlled to yield a spacevelocity (W./h./w.) of -1000 and a catalyst to oil ratio of 0.0140.

3. The method of claim 1 wherein a second stream of hydrocarbon-catalystslurry is withdrawn from the reaction zone and passed into heatabsorption relation with the catalyst undergoing combustion regenerationbefore being returned to the reaction zone.

4. The method of claim 1 wherein the hydrocarbon used for reslurryingthe regenerated catalyst is a portion of the hydrocanbon feed stock.

5. The method of claim 1 wherein the finely divided high activitycatalyst particles comprise a superactive crystalliue aluminosilicate ofordered internal structure.

6. Apparatus for conversion of hydrocarbons comprising in combination, avessel having a lower reactor section containing finely divided solidcatalyst slurried in liquid hydrocarbon, and an upper fractionatingsection in open communication therewith containing a plurality of spacedapart fractionating plates, a first inlet conduit to said reactorsection for introducing liquid feed stock, a first Withdrawal conduitfrom said reactor section for withdrawing hydrocarbon-catalyst slurry, aseparating means connected to said first withdrawal conduit forseparating said slurry into a hydrocarbon stream and solid particlematerial catalyst streams, a solid catalyst particle regeneratingchamber, means for conveying said catalyst particle stream from saidseparating means to said catalyst regenerating chamber, means forconveying regenerated catalyst to a catalyst-hydrocarbon slurry formingmeans, conduit means communicating between said reslurrying means andsaid reactor section, a second conduit means for conveying a slurrystream from said rector section through said regenerating chamber inindirect heat absorption relation with said catalyst undergoingregeneration in said regenerating chamber, and conduit means leadingfrom said regenerating chamber back to said reactor section.

7. Apparatus in accordance with claim 6 wherein a conduit means connectsthe hydrocarbon exit from said separating means to said reslurryingmeans.

8. Apparatus in accordance with claim 6 wherein a conduit means connectsthe feed stock inlet to said reactor zone with said reslurrying means.

9. Apparatus in accordance with claim 6 wherein said conduit means fromsaid regenerating chamber for the recycled slurry stream merges with theconduit from said reslurrying means.

References Cited UNITED STATES PATENTS 2,319,710 5/1943 Stratford et a1.208-153 2,723,949 11/1955 McCausland 208-176 2,763,600 9/1956 Adams etal 208160 3,113,844 12/1963 Hemminger 208 3,198,729 8/1965 Payne 208DELBERT E. GANTZ, Primary Examiner.

A. RIMENS, Assistant Examiner.

1. A METHOD FOR EFFECTING LIQUID PHASE CONVERSION OF HYDROCARBONS WHICHCOMPRISES FORMING A LIQUID PHASE SLURRY OF FRESH HYDROCARBON FEED ANDFINELY DIVIDED HIGH ACTIVITY CATALYST PARTICLES, INTRODUCING SAID SLURRYTO A HYDROCARBON CONVERSION ZONE MAINTAINED UNDER TEMPERATURE ANDPRESSURE CONDITIONS SUFFICIENT TO CONVERT A PORTION OF SAID HYDROCARBONSTO VAPOROUS CONVERSION PRODUCTS, PASSING VAPOROUS HYDROCARBON CONVERSIONPRODUCTS OVERHEAD TO A FRACTIONATION ZONE, REMOVING A FIRST PORTION OFSLURRY FROM THE CONVERSION ZONE, SEPARATING SAID FIRST PORTION INTO ALIQUID HYDROCARBON PHASE AND A CATALYST PARTICLE PHAE, REGENERATING BYCOMBUSTION SAID CATALYST PARTICLES PHASE, RESLURRYING REGENERATEDCATALYST PARTICLES WITH AT LEAST SAID LIQUID HYDROCARBON PHASE ANDRECYCLING RESLURRIED MATERIAL TO SAID CONVERSION ZONE.